added piccolo shell run command

Author: dantownsend

piccolo/apps/shell/__init__.py

@@ -0,0 +1,58 @@
+import sys
+import typing as t
+
+from piccolo.conf.apps import AppRegistry, AppConfig
+from piccolo.table import Table
+
+
+def start_ipython_shell(**tables: t.Dict[str, t.Type[Table]]):
+    try:
+        import IPython
+    except ImportError:
+        print(
+            "Install iPython using `pip install ipython==7.6.1` to use this "
+            "feature."
+        )
+        sys.exit(1)
+
+    existing_global_names = globals().keys()
+    for table_class_name, table_class in tables.items():
+        if table_class_name not in existing_global_names:
+            globals()[table_class_name] = table_class
+
+    IPython.embed()
+
+
+def run():
+    """
+    Runs an iPython shell, and automatically imports all of the Table classes
+    from your project.
+    """
+    try:
+        import piccolo_conf
+    except ImportError:
+        print("Can't find piccolo_conf")
+        sys.exit(1)
+
+    app_registry: AppRegistry = piccolo_conf.APP_REGISTRY
+
+    tables = {}
+    spacer = "-------"
+
+    if app_registry.app_configs:
+        print(spacer)
+
+        for app_name, app_config in app_registry.app_configs.items():
+            app_config: AppConfig = app_config
+            print(f"Importing {app_name} tables:")
+            if app_config.table_classes:
+                for table_class in app_config.table_classes:
+                    table_class_name = table_class.__name__
+                    print(f"- {table_class_name}")
+                    tables[table_class_name] = table_class
+            else:
+                print("- None")
+
+        print(spacer)
+
+    start_ipython_shell(**tables)

piccolo/apps/shell/commands/__init__.py

@@ -0,0 +1,7 @@
+from piccolo.conf.apps import AppConfig
+from .commands.run import run
+
+
+APP_CONFIG = AppConfig(
+    app_name="shell", migrations_folder_path="", commands=[run]
+)

piccolo/apps/shell/commands/run.py

@@ -10,6 +10,7 @@
 from piccolo.apps.migrations.piccolo_app import APP_CONFIG as migrations_config
 from piccolo.apps.playground.piccolo_app import APP_CONFIG as playground_config
 from piccolo.apps.project.piccolo_app import APP_CONFIG as project_config
+from piccolo.apps.shell.piccolo_app import APP_CONFIG as shell_config
 from piccolo.apps.user.piccolo_app import APP_CONFIG as user_config
 
 
@@ -29,6 +30,7 @@ def main():
         migrations_config,
         playground_config,
         project_config,
+        shell_config,
         user_config,
     ]:
         for command in _app_config.commands: